Methylierungsversuche an Stärke

Ohne Zusammenfassung     

Non-Gaussian non-stationary models for natural hazard modeling

This paper addresses the construction of probabilistic models for time or space dependent natural hazards. The proposed method uses Karhunen-Loève expansion in order to construct an empirical model matching the non-stationarity and the randomness of natural phenomena such as earthquakes or other complex environmental processes. The terms of the Karhunen-Loève expansion are identified directly from measured data. The approach is illustrated and its performance assessed through two academic examples. It is then applied to seismic ground motion modeling using recorded data.     

Über die Schmelzwärme von Mischungen schweren und gewöhnlichen Wassers

Zusammenfassung Die Schmelzwärme von H₂O-D₂O-Mischungen wird in einem elektrisch geheizten Mikrokalorimeter bestimmt. Für D₂O wurde 315.1j/g oder 1508 cal/Mol gefunden.     

Integrable almost complex structures in principal bundles and holomorphic curves

We consider almost complex structures that arise naturally in a particular class of principal fibre bundles, where the choice of a connection can be used to determine equivariant isomorphisms between the vertical and horizontal tangent bundles of the total space. For instance, such data always exist on the frame bundle of a 3-manifold, but also in many other situations. We study the integrability condition to a complex structure, obtaining a system of gauge invariant coupled first order partial differential equations. This yields to a few correspondences between complex-geometric properties on the total space and metric properties on the base.     

A note on logarithmic transformations on the Hopf surface

In this note we study logarithmic transformations in the sense of differential topology on two fibers of the Hopf surface. It is known that such transformations are susceptible to yield exotic smooth structures on 4-manifolds. We will show here that this is not the case for the Hopf surface, all integer homology Hopf surfaces we obtain are diffeomorphic to the standard Hopf surface. To cite this article: R. Zentner, C. R. Acad. Sci. Paris, Ser. I 342 (2006).     

Kinematic analysis of a rolling tensegrity structure with spatially curved members

In this work, a tensegrity structure with spatially curved members is applied as rolling locomotion system. The actuation of the structure allows a variation of the originally cylindrical shape to a conical shape. Moreover, the structure is equipped with internal movable masses to control the position of the center of mass of the structure. To control the locomotion system a reliable actuation strategy is required. Therefore, the kinematics of the system considering the nonholonomic constraints are derived in this paper. Based on the resulting insight in the locomotion behavior a feasible actuation strategy is designed to control the trajectory of the system. To verify this approach kinematic analyses are evaluated numerically. The simulation data confirm the path following due to an appropriate shape change of the tensegrity structure. Thus, this system enables a two-dimensional rolling locomotion.

     

Mechanism of water transport in controlled porosity osmotic devices

Controlled drug delivery devices that release the drug from an osmotic core by a pumping mechanism are promising for the oral administration of water-soluble drugs. This study considers various possible paths for the transport of water through a porous cellulose acetate membrane which constitutes the outer wall of a particular osmotic device. It is shown that the mechanism of water transport is not solely by diffusion through the semipermeable cellulose acetate or water-filled voids: solute-excluding water-filled regions in the coat as well as the polymeric portion of the coat are important in water ingress into the osmotic pump.